The term "rubber modified copolymer of a vinyl aromatic compound and an .alpha.,.beta.-unsaturated cyclic anhydride" is used to generically designate a class of materials that are exemplified by rubber modified styrene-maleic anhydride. These materials are well known and are commerically available as a thermoplastic molding composition. The impact strengths of this material has been relatively low and therefore it has been desirable to upgrade the physical properties of this material. Applicant has found that compositions of a rubber modified copolymer of a vinyl aromatic compound and an acrylic graft polymerization copolymer have increased Izod impact strength and good heat distortion temperatures. Also, the addition of a poly(2,6-dimethyl-1,4-phenylene) resin to this composition will further enhance the impact strength and will also provide a composition with a high distortion temperature.
Accordingly, it is a primary object of the present invention to provide compositions of a rubber modified copolymer of a vinyl aromatic compound an an .alpha.,.beta.-unsaturated copolymer having improved impact strength.
It is also an object of the present invention to provide compositions of a rubber modified copolymer of a vinyl aromatic compound an an .alpha.,.beta.-unsaturated copolymer having improved heat distortion temperature.